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Wednesday, April 22, 2015

Caught by surprise

They caught me by surprise:

It's been a good year for Painted Ladies (Vanessa cardui), but today numbers were noticeably higher.

While photographing one for the record, I noticed another species nearby:

This Red Admiral (Vanessa atalanta) was also nectaring on Sea Thrift (Armeria maritima) along the Bodega Head bluffs.

Not long after this, I flushed a large dragonfly (a darner) from near the trail. Interestingly, its wings were shiny, indicating an individual that had emerged from a wetland not too long ago.

And then I saw this butterfly land among the grasses momentarily:

Orange Sulphurs (Colias eurytheme) are common inland, but I only seen them occasionally on Bodega Head.

I've mentioned before that Bodega Head is not the best place for butterflies and dragonflies —
it's generally too cold with strong northwest winds coming off the ocean. However, there are certain conditions that create potential for interesting insect viewing —
e.g., when the winds are from the south or east and the thermometer rises.

The strange thing about today was that I hadn't really noticed these conditions, and there were lots of butterflies and at least a sign of dragonfly movement along the coast.

Had I just missed it? I looked back at the weather data for the last few days. The maximum air temperatures were about 57°F and 58.5°F. Those temperatures are about average, and in fact it was warmer earlier in the month.

Then I looked at the wind. I checked for the percentage of winds that came from the south, south-southwest, and south-southeast during the last few days. Here's what those percentages looked like:

April 22 —
~15%

April 21 —
~14%

April 20 —
~35%

Below is a visual representation of the winds on April 20th:

Did the winds on Monday, April 20, encourage a strong northward push of butterflies and dragonflies?

I don't know, but it's worth keeping an eye out for these events and noting the weather around them.

1 comment:

Alice Chan
said...

Love these butterflies and thinking about which winds bring them in. Now I'm wondering about West Coast Ladies. As far as I can remember, we had them in profusion until about six years ago, but now I never see them anymore. Any thoughts?